Recently we have developed a simple, noninvasive, and safe procedure for imaging the area of damage in patients with acute myocardial infarction using technetium-99m stannous pyrophosphate. The objective of this proposed research is to 1) further develop this imaging technique, 2) determine the exact site and mechanism of uptake of the Tc99m-phosphates in the damaged tissue at the cellular and subcellular level using autoradiographic and elemental analysis techniques, 3) investigate why the Tc99m-phosphate localization in the infarcted tissue is time-dependent, 4) correlate histological and scintigram estimates of infarct size in experimental animals, 5) develop and test analytical techniques for measuring infarct size using the scintigrams and a typical nuclear medicine minicomputer system, 6) use the new imaging technique to determine the true incidence of myocardial infarction in patients with coronary bypass surgery and myocardial trauma, 7) study a large group of patients to clinically evaluate the technique's ability to size acute infarcts and detect extensions of acute myocardial infarctions, 8) examine patients with other forms of chest disease, specifically those with myocardial and pericardial disease, in order to determine when the scintigrams may be positive other than in acute myocardial infarction. BIBLIOGRAPHIC REFERENCES: Stokely E.M., Buja L.M., Lewis S.E., Parkey R.W., Bonte F.J., Harris R.A., Jr., Willerson J.T.: Sizing of acute myocardial infarcts in dogs with technetium-99m stannous pyrophosphate myocardial scintigrams. J. Nucl. Med., In press, Jan. 1976. Parkey R.W., Bonte F.J., Stokely E.M., Curry G.C., Willerson J.T.: Measurement of myocardial blood flow. Critical Reviews in Rad. and Nuc. Med., CRC Press, Cleveland, Ohio 6:33, pp. 441-458, 1975.